is there a specific reason you want the rod to be the thing that motivates the wheel? Is it because you need the slider to control the percentage of stroke of the rod instead of the amount of wheel rotation?
As for what is happening (writing from home, not in front of the definition, so there might be some discrepancy between my memory and reality (often the case )), the angle slider rotates the wheel and a reference point, the arm is then moved from the reference point’s original location to the new rotated location. In the first option, that’s all that is going on.
In the second option, I’m also drawing a line along the center of the arm, which represents the direction of travel for the fixed end. I then draw a circle the same radius as the arm and rotate that with the wheel and the reference point. Where the circle and line intersect is where the end of the rod wants to land. I then used an orient module to move and rotate the arm.